Yeah its pretty complicated to say the least and US involvement in the region has been has spectacular disaster since they first started to get involved. Which was pretty much since the collapse of the ottoman empire.
What I will say is that attempts to topple dictatorships, particular the secular dictatorships in the region, have largely had disastrous consequences. From the Russians with Afghanistan, to the US with Iraq, and now what is happing in Syria which is perhaps a more authentic revolt. Obviously I now think Assads position is unattainable cause of the war crimes committed but before the war he was far from the worst in the region (yes bit of a tallest dwarf scenario here) . Brutal towards his enemies for sure but coming from an Alawite minority makes him far safer to the Druze and Christian minorities then a Sunni government would. Even a democratic Sunni government if the Muslim Brotherhood in Egypt anything to go by..
A Lebanese styled democracy (without the corruption and complete ineffectiveness) might be ideal. Where all the groups are represented and have checks on each other. Where one sect can not dominate all the branches of government. But I think its far too late for that unfortunately. Assad reacted violently to the peaceful protests and now we are in this mess. Syria as a single united country I think is now over. The chance for peace and perhaps negotiated redrawn boundaries can only exists once ISIL dont have a stake in Syria. Because they are not a group who are going to live and let live. They are not going to agree to any peace talks because their goal isnt governance nor a piece of land. It is a destruction of modern society.
What we absolutely dont need right now is a full frontal attack against a government that right now is one of the major oppositions against ISIL. Which will cause huge Russia/US tension and could start a world war further down the line. Anything that further escalates towards nuclear war is a bad choice in my books. Right now focus on the common enemy while supporting alternatives to Assad.